1. Field of the Invention
(A) This invention generally relates to multi-contact connectors.
(B) More specifically, the invention relates to multi-contact spread connectors for seismic cables.
2. Description of the Prior Art
Multi-contact connectors are widely used in various technical fields. While this invention is not limited to the seismic prospecting field, it will be described as having particular utility thereto. In the seismic art, multi-contact connectors are known as "spread" connectors which are adapted for interconnecting the electric conductors of geophone spread cables. Each electric conductor carries the signal from one or more geophones; the signal a seismic trace on a suitable recorder. A faulty pair of contacts in any one of the spread connectors will cause the complete loss of the signal and hence loss of the corresponding seismic trace.
Since geophysical work is carried out in adverse environments, the spread connector typically becomes subjected to dirt, sand, water, mud, etc. Even though the contacts are usually mounted in waterproof housings, the contacts unavoidably become dirty requiring frequent cleaning thereof.
Most commercially available spread connectors employ pin and socket terminals although because of their convex surfaces, the pins are relatively easy to clean, dirt deposited inside the sockets is rather difficult to dislodge. Normally, mechanical contact is established between the outer wall of the pin and the inner wall of the socket, with the pin exerting radial pressure against the socket in a plane transverse to the direction of the axial force producing the engagement therebetween. This constitutes a very inefficient mode of force transfer. Thus, even when an adequate axial force is applied onto the pin, there can result an inadequate mechanical pressure contact between the pin and the socket. A poor pressure contact between a pin and its socket may cause undesirable attenuation of the signal carried by the electric conductor connected thereto, or even a complete loss of signal.
The design of conventional pin-and-socket plugs for use in spread connectors requires that their contacts be precision manufactured and accurately aligned, both in the vertical and horizontal directions relative to the plug's end face. Such precision machining and assembly makes the cost of manufacturing conventional spread connectors relatively high. When a conventional spread connector requires servicing, either because its contacts are dirty or because some of its contacts break or become misaligned, such service can frequently not be accomplished in the field. As a result, an expensive spread connector is likely to become discarded just because of the inability or difficulty of servicing it in the field.
Other problems associated with known spread connectors are caused by their geometric configurations which make them objectionable for use with seismic spread cables. These problems are aggravated by the fact that seismic field crews are frequently composed of relatively inexperienced personnel, who have difficulty locating a problem associated with a multi-contact connector and making the required field repairs thereto.
Some of the above-mentioned problems have been solved by the invention described in U.S. Pat. No. 4,045,107. Although the above patent discloses an improved two-plug connector in respects of cost of manufacturing, ease of servicing, and reliability in operation under very adverse field conditions, the connector is not easily field repairable.